This invention relates to organic additives for suppressing particulate emissions and hydrocarbon fuels containing the additives. These additives are useful for reducing soot, smoke and particulate emissions from hydrocarbon fuels.
The petroleum industry has encountered numerous problems in supplying hydrocarbon fuels, especially middle distillate fuels suitable for use in compression ignition and jet engines. One problem associated with combustion of hydrocarbon fuels in these engines is that they contribute materially to pollution of the atmosphere through soot, smoke and particulate emissions in engine exhaust gases.
The particulate matter formed in combustion of hydrocarbon fuels, especially middle distillate fuels, such as diesel fuels, and residual fuels, such as non-distillate fuel oils, is commonly referred to as soot. When present in sufficient particle size and quantity, soot in engine, boiler or burner exhaust gases appears as a black smoke. Soot formation in exhaust gases is highly undesirable since it causes environmental pollution, engine design limitations, and possible health problems.
Diesel-type engines are well known for being highly durable and fuel efficient. Because of this durability and fuel efficiency, diesel-type engines have long been used in heavy-duty motor vehicles, such as trucks, buses and locomotives. Recently, however, the automotive industry is using diesel-type engines in passenger automobiles and light-duty trucks to achieve greater fuel economy and conserve gasoline. This increased use of diesel-type engines materially adds to pollution of the atmosphere through increased soot, smoke and particulate emissions from engine exhaust gases.
Several attempts have been made to reduce emissions from diesel-type engines through the use of additives to middle distillate fuels. For example, U.S. Pat. No. 3,817,720 relates to organic smoke suppressant additives and distillate hydrocarbon fuels containing the same. The preferred organic additives are ethers of hydroquinone. These compounds are ethers of phenolic-type compounds which contain two oxygen atoms attached to each phenyl moiety.
The suppression of particulate emissions from diesel engines is described in U.S. Pat. No. 4,240,802, which discloses the addition of a minor amount of a cyclopentadienyl manganese tricarbonyl and a lower alkyl or cycloalkyl nitrate to a hydrocarbon fuel. These compounds are described as useful in reducing particulate emissions of fuel oil.
It is an object of the present invention to provide liquid hydrocarbon fuel compositions heavier than gasoline having enhanced properties for suppressing particulate emissions.
Another object of the present invention is to provide a middle distillate fuel composition having properties for reducing soot and smoke emissions.
Other objects and advantages of the invention will be apparent from the following description.